uboot-imx

linux, compat: add missing definitions for ubi

add missing definitions for the ubi/ubifs sync
with linux 4.2, also change "#define kfree ..."
into a static inline, so prevent ubi compile error:

   CC      drivers/mtd/ubi/fastmap.o
drivers/mtd/ubi/fastmap.c: In function 'scan_pool':
drivers/mtd/ubi/fastmap.c:475:3: error: called object 'free' is not a function

Signed-off-by: Heiko Schocher <hs@denx.de>